When a wildfire strikes California, the state's efforts to stop global warming go up in smoke.

A study released March 12 of four large California wildfires shows they collectively will put an estimated 38 million tons of greenhouse gases into the atmosphere through fire and subsequent decay of dead trees. Together emissions from fire and decay undo much of the progress California is making to fight global warming. The estimated 38 million tons of greenhouse gases is the equivalent of emissions from seven million cars - for one year. Nearly 10 million tons of harmful greenhouse gases were emitted from the fires themselves, with an estimated 28 million additional tons of carbon dioxide emitted from decay, mostly in the next 50 years.

"Reducing the number and severity of wildfires may be the single most important action we can take in the short-term to lower greenhouse gas emissions and fight global warming," said Dr. Thomas Bonnicksen, a noted forestry expert who authored the report and has studied California forests for more than 30 years.

The study was conducted for the Forest Foundation, a nonprofit organization that promotes education about the state's forests. The study is based on an analytical tool developed for the Forest Foundation that allows scientists to estimate greenhouse gases emitted by wildfire and subsequent forest decay. The tool, called the Forest Carbon and Emissions Model, analyzes the impact of wildfires on global warming by considering a number of factors, including vegetation density, tree species, mortality caused by a fire, and the removal of dead trees and replanting of new trees.

The study included extensive analysis of four fires:

- The Angora Fire, which burned more than 3,100 acres near South Lake Tahoe in June and July of 2007.

- The Fountain Fire, which destroyed nearly 60,000 acres east of Redding in August 1992.

- The Star Fire, which burned more than 16,000 acres in September 2001 in the Tahoe and Eldorado National Forests.

- The Moonlight Fire, which burned more than 65,000 acres in September 2007 in and around the Plumas National Forest in the northern Sierra Nevada.

Even today, fires that ended months and years ago are still releasing carbon dioxide into the atmosphere as dead trees left in the forest continue to decay.

Bonnicksen added that "removing dead trees and replanting to restore the forest can reverse the impact of wildfires on global warming by recovering most - if not all - of the carbon dioxide lost to the atmosphere from fire and decay." In addition, he said, "it would also help protect surrounding forests and communities from a second wildfire or re-burn, which often occurs in un-restored forests that become brush fields filled with dead trees."

Unfortunately, Bonnicksen noted, the federal government doesn't move quickly to remove fire-killed trees and replant. For the Angora and Moonlight fires of 2007, no removal of dead trees has occurred on federally owned lands and there is no plan to replant those areas. In contrast, private forest landowners swiftly remove dead trees, turning them into wood products used by consumers, rather than allow them to decay and send carbon dioxide into the air, and then they replant a new forest.

"These wood products continue to store carbon and a young, replanted and well-managed forest absorbs carbon at a fast rate," Bonnicksen said. "If we care about our forests and fighting global warming then we must reduce the threat of wildfire and remove dead trees and replant if a wildfire occurs."

For a copy of the full report, visit www.calforestfoundation.org.